java 实现DFA 算法（理论百度搜索）

DFA简介

DFA全称为：Deterministic Finite Automaton,即确定有穷自动机。（自己百度吧）

直接代码：

敏感词实体类

package com.nopsmile.dfa;

public class Keywords {
    private String pid;
    private String Content;

    public Keywords() {

    }

    public Keywords(String content) {
        super();
        Content = content;
    }

    public String getContent() {
        return Content;
    }

    public void setContent(String content) {
        Content = content;
    }

    public String getPid() {
        return pid;
    }

    public void setPid(String pid) {
        this.pid = pid;
    }

}

敏感词库初始化

package com.nopsmile.dfa;
import java.util.HashMap;
import java.util.HashSet;
import java.util.Iterator;
import java.util.List;
import java.util.Map;
import java.util.Set;

/**
 * 敏感词库初始化
 * 
 */
public class SensitiveWordInit{

    /**
     * 敏感词库
     */
    public HashMap sensitiveWordMap;

    /**
     * 初始化敏感词 keywords
     */
   public Map initKeyWord(List<Keywords> sensitiveWords) {
        try {
            // 从敏感词集合对象中取出敏感词并封装到Set集合中
            Set<String> keyWordSet = new HashSet<String>();
            for (Keywords s : sensitiveWords) {
                keyWordSet.add(s.getContent().trim());
            }
            // 将敏感词库加入到HashMap中
            addSensitiveWordToHashMap(keyWordSet);
        } catch (Exception e) {
            e.printStackTrace();
        }
        return sensitiveWordMap;
    }

    /**
     * 封装敏感词库
     */
    private void addSensitiveWordToHashMap(Set<String> keyWordSet) {
        // 初始化HashMap对象并控制容器的大小
        sensitiveWordMap = new HashMap(keyWordSet.size());
        // 敏感词
        String key = null;
        // 用来按照相应的格式保存敏感词库数据
        Map nowMap = null;
        // 用来辅助构建敏感词库
        Map<String, String> newWorMap = null;
        // 使用一个迭代器来循环敏感词集合
        Iterator<String> iterator = keyWordSet.iterator();
        while (iterator.hasNext()) {
            key = iterator.next();
            // 等于敏感词库，HashMap对象在内存中占用的是同一个地址，所以此nowMap对象的变化，sensitiveWordMap对象也会跟着改变
            nowMap = sensitiveWordMap;
            for (int i = 0; i < key.length(); i++) {
                // 截取敏感词当中的字，在敏感词库中字为HashMap对象的Key键值
                char keyChar = key.charAt(i);

                // 判断这个字是否存在于敏感词库中
                Object wordMap = nowMap.get(keyChar);
                if (wordMap != null) {
                    nowMap = (Map) wordMap;
                } else {
                    newWorMap = new HashMap<String, String>();
                    newWorMap.put("isEnd", "0");
                    nowMap.put(keyChar, newWorMap);
                    nowMap = newWorMap;
                }

                // 如果该字是当前敏感词的最后一个字，则标识为结尾字
                if (i == key.length() - 1) {
                    nowMap.put("isEnd", "1");
                }
            }
        }
    }
}

自定义的工具类

package com.nopsmile.dfa;

import java.util.ArrayList;
import java.util.Collections;
import java.util.Comparator;
import java.util.HashMap;
import java.util.HashSet;
import java.util.Iterator;
import java.util.LinkedHashMap;
import java.util.LinkedList;
import java.util.List;
import java.util.Map;
import java.util.Set;

import com.alibaba.fastjson.JSONArray;

import net.sf.json.JSONObject;

/**
 * 敏感词过滤工具类
 * 
 * @author AlanLee
 *
 */
public class SensitivewordUtils {
    /**
     * 敏感词库
     */
    public static Map sensitiveWordMap = null;

    /**
     * 只过滤最小敏感词
     */
    public static int minMatchTYpe = 1;

    /**
     * 过滤所有敏感词
     */
    public static int maxMatchType = 2;

    /**
     * 敏感词库敏感词数量
     *
     * @return
     */
    public static int getWordSize() {
        if (SensitivewordUtils.sensitiveWordMap == null) {
            return 0;
        }
        return SensitivewordUtils.sensitiveWordMap.size();
    }

    /**
     * 是否包含敏感词
     *
     */
    public static boolean isContaintSensitiveWord(String txt, int matchType) {
        boolean flag = false;
        for (int i = 0; i < txt.length(); i++) {
            int matchFlag = checkSensitiveWord(txt, i, matchType);
            if (matchFlag > 0) {
                flag = true;
            }
        }
        return flag;
    }

    /**
     * 获取敏感词内容
     *
     * @param txt
     * @param matchType
     * @return 敏感词内容
     */
    public static Set<String> getSensitiveWord(String txt, int matchType) {
        Set<String> sensitiveWordList = new HashSet<String>();

        for (int i = 0; i < txt.length(); i++) {
            int length = checkSensitiveWord(txt, i, matchType);
            if (length > 0) {
                // 将检测出的敏感词保存到集合中
                sensitiveWordList.add(txt.substring(i, i + length));
                i = i + length - 1;
            }
        }

        return sensitiveWordList;
    }

    /**
     * 替换敏感词
     *
     */
    public static String replaceSensitiveWord(String txt, int matchType, String replaceChar) {
        String resultTxt = txt;
        Set<String> set = getSensitiveWord(txt, matchType);
        Iterator<String> iterator = set.iterator();
        String word = null;
        String replaceString = null;
        while (iterator.hasNext()) {
            word = iterator.next();
            replaceString = getReplaceChars(replaceChar, word.length());
            resultTxt = resultTxt.replaceAll(word, replaceString);
        }

        return resultTxt;
    }

    /**
     * 替换敏感词内容
     *
     */
    private static String getReplaceChars(String replaceChar, int length) {
        String resultReplace = replaceChar;
        for (int i = 1; i < length; i++) {
            resultReplace += replaceChar;
        }

        return resultReplace;
    }

    /**
     * 检查敏感词数量
     *
     */
    public static int checkSensitiveWord(String txt, int beginIndex, int matchType) {
        boolean flag = false;
        // 记录敏感词数量
        int matchFlag = 0;
        char word = 0;
        Map nowMap = SensitivewordUtils.sensitiveWordMap;
        for (int i = beginIndex; i < txt.length(); i++) {
            word = txt.charAt(i);
            // 判断该字是否存在于敏感词库中
            nowMap = (Map) nowMap.get(word);
            if (nowMap != null) {
                matchFlag++;
                // 判断是否是敏感词的结尾字，如果是结尾字则判断是否继续检测
                if ("1".equals(nowMap.get("isEnd"))) {
                    flag = true;
                    // 判断过滤类型，如果是小过滤则跳出循环，否则继续循环
                    if (SensitivewordUtils.minMatchTYpe == matchType) {
                        break;
                    }
                }
            } else {
                break;
            }
        }
        if (!flag) {
            matchFlag = 0;
        }
        return matchFlag;
    }

    /**
     * 敏感词汇对应个数
     * 返回 "关键字"="关键字个数"
     *
     */
    public static Map getSensitiveWordSum(String txt, int matchType) {
        Map<String,Integer> map = new HashMap<String,Integer>();
        for (int i = 0; i < txt.length(); i++) {
            int length = checkSensitiveWord(txt, i, matchType);
            if (length > 0) {
                // 将检测出的敏感词保存到集合中
                String str=txt.substring(i, i + length);
                if(map.containsKey(str)) {
                    map.put(str, map.get(str).intValue()+1);
                }else {
                    map.put(str, new Integer(1));
                }
                //System.out.println(txt.substring(i, i + length));
                i = i + length - 1;
            }
        }
        return map;
    }

    /**
     *  对map数组value排序，并取前10
     *  this method will always sort the map;
     *  isCondition is true condition can be used otherwise invalid
     * @param unsortMap
     * @return
     */
    public static Map<String, Integer> sortByValue(Map<String, Integer> unsortMap,int condition,boolean isCondition) {

        // 1. Convert Map to List of Map
        List<Map.Entry<String, Integer>> list =
                new LinkedList<Map.Entry<String, Integer>>(unsortMap.entrySet());

        // 2. Sort list with Collections.sort(), provide a custom Comparator
        //    Try switch the o1 o2 position for a different order
        Collections.sort(list, new Comparator<Map.Entry<String, Integer>>() {
            public int compare(Map.Entry<String, Integer> o1,
                               Map.Entry<String, Integer> o2) {
                return (o2.getValue()).compareTo(o1.getValue());
            }
        });

        // 3. Loop the sorted list and put it into a new insertion order Map LinkedHashMap
        Map<String, Integer> sortedMap = new LinkedHashMap<String, Integer>();
        if(isCondition) {
            for (int i = 0; i < list.size(); i++) {
                if (i < condition) {
                    sortedMap.put(list.get(i).getKey(), list.get(i).getValue());
                }
            }
        }else{
            for (int i = 0; i < list.size(); i++) {
                    sortedMap.put(list.get(i).getKey(), list.get(i).getValue());
            }
        }
        return sortedMap;
    }

}

使用上面类流程代码

Keywords ss=new Keywords("好");
List list = new ArrayList();
list.add(ss);

SensitiveWordInit sensitiveWordInit = new SensitiveWordInit();
Map sensitiveWordMap   = sensitiveWordInit.initKeyWord(list);

// 传入SensitivewordEngine类中的敏感词库
SensitivewordUtils.sensitiveWordMap = sensitiveWordMap;

SensitivewordUtils.getSensitiveWordSum("需要检测的文本", 2)    ；